Most countries have abolished the death penalty. The United States retains the death penalty, although it has attempted to make executions more humane. The [Page 187]Supreme Court has restricted use of the death penalty based on the type of crime and the characteristics of the criminal. Psychologists and other social scientists have conducted research on issues such as whether the death penalty serves as a deterrent, what drives public support for capital punishment, how jurors decide whether to sentence a defendant to life in prison or death by execution, and the possibility of wrongful convictions and executions.